1. Field of the Invention
The present invention relates to control of model airplanes or gliders and the like, and more specifically to an automatic elevator control for improving the flight performance of model airplanes or gliders.
2. Description of the Prior Art
Non-powered model airplanes such as gliders are extremely popular. The most common type of glider airplane is designed for hand launching; however, the altitude to which the glider can be launched and the resulting flight times are relatively limited. The use of a sling shot or catapult type launcher can impart a higher initial velocity to the plane and theoretically allow a much greater altitude to be achieved before free flight would begin. However, it is necessary to slightly raise the elevators to maintain a high angle of attack in normal free-flight glide. Unfortunately, the high velocity of the launch and the resulting slip stream over the raised elevators can force the model into a looping climb generally followed by a high speed dive. At worst, the dive may carry the model into the ground with subsequent damage, or at best, the model may pull out very close to the ground which obviously limits the free flight time. These disadvantages have limited the catapult launched gliders to simple, cheaply made models with expectation of limited lifetimes.
Thus, there is a need for a sling shot or catapult launched glider type model airplane in which the elevators are set at launch to allow a straight vertical climb until the energy imparted by the launching device is dissipated and, at that point, to permit the elevators to assume a desired optimum glide position.
Control of elevators in flight have been disclosed in U.S. Pat. Nos. 3,757,462 and 3,745,699, both to Mabuchi. However, these controls operate electrically in powered models to assist in the landing phase. A manually settable elevator system is disclosed in U.S. Pat. No. 2,156,741 to Sellers and a stabilizing control is taught by Doyle, U.S. Pat. No. 2,454,598. However, none of this prior art is applicable to an automatic elevator control for power-launched gliders.